Process for the production of fluorochloromethanes



May 6, 1969 VECCHIO ETAL 3,442,962

PROCESS FOR THE PRODUCTION OP FLUOROCHLOROMETHNES FiledM.rch2l. 1966 so HF Conversion F ig.1

Recycle. CH., Rafio Fig.2

Rccycle CH, Raffo Moles Fluorinafed Chloromefhanes 2* Per HL; Per Lifer of Cafalys1 Fig.3

1''si's1'ofi1'2 Recycle. CH Rafio Marfino Vecchio I 1a/o Cammarafa Luciano Lodi INVEN TOR s Attomey United States Patent Ofice 3,442,962 PROCESS FOR THE PRODUCTION OF FLUOROCHLOROMETHANES Martino Vecchio, Italo Cammarata, and Luciano Lodi, Milan, Italy, assignors to Montecatini Edison S.p.A.,

Milan, Italy, a corporation of Italy Filed Mar. 21, 1966, Ser. No. 536,596 Int. Cl. C07c 17/10 U.S. Cl. 260-653.7 4 Claims ABSTRACT OF THE DISCLOSURE between 180 and 700 C. and for a catalyst-contaot time between 0.1 and 30 seconds and continuously separating the reaction-products mixture into a recycle mixture, substantially egual in amount and composi-tion to the recycle mixture passed over the catalyst together with methane, chlorde, and hydrogen fluor-ide, and into a reeovered product consisting essentially of the desired monoand difluorochloromethanes.

This applcation is a continuation in part of our applications Ser. No. 219,777, filed Aug. 27, 1962, (now abandoned), Ser. No. 294,250, filed July 11, 1963, (now U.S. Patent No. 3,294,852), Ser. No. 367,895, filed M-ay 15, 1964, and Ser. No. 461,884, filed June 7, 1965 (both now -abandoned) The aforementioned copending applications relate to continuous processes for the produetion of fluorine-containing completely halogenated methanes, namely, chlorofluorinated methanes, by the continuous reaotion of nonhalogenated methane With chlorine and hydrogen fluoride in the presence of a catalyst and of at least one halogenated hydrocarbon, preferably having a skeleton similar to that of the nonhalogenated hydrocarbon, whose funetion and etfectiveness will be discussed in greater detail hereinbelow.

It has already been proposed to carry out a fluorinaton of chlorinated organic compounds both in liquidand vapor-phase reaotions. Thus a liquid-phase reaction can involve the refluxing, under pressure, of a mixture of hydrogen fluorde (HF) with a halogenated organic compound, e.g., halogenated aliphatic hydrocarbons of the chloromethane type, in the presence of antimony halides. The vapor-phase processes practiced heretofore involve the passing of a mixture of hydrogen fluoride and one or more halogenated organc compounds over catalysts generally ehosen from among the aluminum, chrornium, zirconum and thorium fluorides. Both the liquid-phase and the vapor-phase processes require halogenated organic compounds as the starting material and may be considered, in part, to involve the replacement of a hgher halogen such as chlorine With fluorine. The starting material must, in turn, be produced by halogenation (e.g., thermal chlorination) of nonhalogenated hydrocarbons.

It has also been suggested that it is possble to obtain fluornated organc derivatves by passing a mixture of hydrogen fluoride, chlorine and methane over a chromum 3,442,962 Patented May 6, 1969 fluoride catalyst. Although this process requires only convenient starting materials, there is no overall improvement in the economy of the process as compared with those mentioned earlier since the reaction velocity in the latter case is extremely slow and catalyst-contact times of about 3 minutes are requred Io obtain any appreciable yields; moreover, the yield per unit of catalyst volume or weight employed is extremely small in spite of the long contact times.

Other gas-phase processes required the presence of oxygen in the gas mixture, and thereby give rise to the formation of water, the presence of this substance being disadvantageous as a consequence of the increased corrosion of the apparatus used for carrying out the reaction; furtherrnore the resulting yields are very low.

The prior conoepts in this field can be considered together in terms of their inherent disadvantages. For exampie, appreciable reacton rates could be obtained heretofore only when the more expensive, halogenated hydrocarbons served as the starting materia]. When nonhalogenated hydrocarbons were employed at lower cost for this starting material, a reduced react-ion rate and a low catalyst utilization increased the cosi: in other respects; the most desired products (e.g., CC1 F and CF C1 were, moreo'ver, obtained in relatively low yields. It has now been found, as set forth in the aforernentioned copending applicati0ns, that it is possible to obtain fluorinated organic compounds and especially ehlorofluornated methanes with very high re-action velocit-ies or rates and With excellent yields, by a process which involves the recycling of one or more halogenated hydrocarbons from the product mxture to the reaction mixture to serve as a reaction promoter and modifier and also to be brought to the desired level of halogenation in the reaction zone.

It is, therefore, an important object of the present invention to provide a process for the production of fluorinated hydrocarbons in general, and completely chlorofluorinated methanes in particular, which extends the principles first set forth in our copending applications mentioned above and penrnits the continuous reaction of nonhalogenated methane in the vapor phase With high yields and reaction rates.

Another object of the present invention is to provide a process for the chlorofluorination of methane which permits the recovery of halomethanes having all of their hydrogen -atorns replaced by fluorine or by fluorine and chlorne while passing through the reaction system.

It is still another objeet of this invention, constitutng a departure from the possibilities of prior techniques in this field, to obtain selectively or preferentially chlorofluorinated compounds, i.e., monofluorotrichloro, dichlorodifluoro and tr-ifluoromonochloro derivatives, from nonhalogenated methane.

Still another object of our invention is to provide a relatively simpie and highly economical process for producing chlorofluorinated products with a high ratio of desired products to catalyst employed as may be deduced, for example, from the 1ow contact times.

A more specific object of the instant invention is to provide a process of the character described which a1- lows the gas-phase reacton temperature to be conveniently and eiectively controlled although the reaction may be highly exothermal.

Still another object of this invention is to provide a process for the chlorofluorination of methane which can be select-ively direc-ted toward the optimum production of one or another chlorofluorinated compound by regulating certan parameters of the recycling stream.

These objects and others which Will become apparent hereinafter are attaned, in accordance With the present invention, via a process involvng the admixture with the nonhalogenated methane of at least one halogenated hydrocarbon recycled from the product mixture and present in an amount preferably comparatively large with respect to the molar quantity of the strating nonhalogenated methane.

The recycled portion of the eflluent at the product side of the reaction zone, including chlorinated methanes as well as chlorofluorinated hydrocarbons, functions not only as a temperature-controlling diluent and reaction participant but also, for reasons not wholly understood, as a reaction promoter markedly increasing the reaction rate and conversion yield to a surprisingly and unexpectedly high degree.

In its broadest aspects, the present invention comprises a process for the production of predetermined chlorofluorinated methanes from nonhalogenated methane which involves the steps of passing methane over a fluorination catalyst used alone or together with a chlorination catalyst in at least one reaction zone maintained at a temperature between substantially 180 C. and 700 C., together with hydrogen fluoride and chlorine for a catalyst-contact time between substantially 0.1 and 30 seconds and in the presence of at least one of the aforementioned recycled halogenated hydrocarbons to fluorinate the methane, the recycled compounds being present in a molar quantity in the range from 0.5 to 15 per mole of nonhalogenated (i.e., starting) methane; the product mixture removed from the reaction zone consists mainly of chlorinated and chlorofluorinated methanes which are separated so that a quantity of halogenated recycled hydrocarbons equal to that admixed with the reactants can be returned to the reaction zone and the process continued.

By the contact time is meant the ratio between the catalyst volume, measured by reading the volume occupied by the catalyst when inserted in the reactor or in a graduated glass cylinder, and the volume of the reactant gases fed to the reaction zone per second in accordance with the relationship:

volume of catalyst contact time= gas volume/seoond tioned fluornation catalysts used alone or associated with any of the conventional chlorination catalysts. Examples of useful catlaysts are oxides or salts and particularly fluorides and chlorides of Cr, Ni, Co, Al, Ga, V, Zr, Th, Zn, Fe, Pd, Cu, Bi, Pb, and their mixtures.

The catalyst, which is preferably in a solid state, may be used alone or on a suitable carrier in a fixed, mobile or fluid bed. Examples of suitable carriers are active carbon, aluminas, fluorinated aluminas and barium sulphate. Those catalysts which are impregnated into or distributed on solid supports preferably having inherent catalytic activity, such as activated carbons and fluorinated aluminas, are, according to this invention, preferably activated by a beat treatment in the presence of a gas at a temperature between substantially 200 C. and 700 C. While generally the temperature range of substantially 180 C. to 700 C. is etfective as indicated earlier, when using a single reaction zone it is preferred to operate within a range of substantially 400 C. to 500 C. since at the lower temperatures (e.g. below 250 C.) the reaction rate falls ot in accordance with the reaction kinetics while at higher temperatures (e.g., above 700 C.) there appears to be a tendency toward decomposition of the organic compounds and the deposition of carbonaceous residues on the surface of the catalyst with consequent lowering of its catalytic activity. One of the significant improvements of this invention over conventional system employing nonhalogenated hydrocarbons as the starting material is that a relatively prolonged contact time on the order of minutes is required in the prior process, whereas the method of the present invention, in spite of a dilution of the nonhalogenated hydrocarbon, permits low contact times and, moreover, gives optimum results at contact times between 1 and 10 seconds, although acceptable yields of fluorinated products are obtained when the contact time is increased to as long as 30 seconds or reduced to 0.1 second. It has been noted that generally, within the stated range, the longer the contact time, the greater is the degree of fluorination.

The raw material, which is converted into fluorinated and chlorofluorinrfled methanes by the process according to this invention, is methane. The halogenated hydrocarbons recycled from the product side of the reaction zone to the reactant side can thus be the chlornated and/or chlorofluorinated derivatives of methane; when operating continuously, quantities of some other products (such as for example tetrachloroethylene, hexachloroethane, perchlorobutadiene, hexachlorobenzene) may be used in addition. In general, however, it may be stated that the composition of the recycled halogenated hydrocarbon mixture determnes the composition of the mixture on the product side Of the reaction zone and thus the predominant product, thereby enabling the distribution of the principal products to be varied, e.g., by modification of the molar ratio of the several balogenated hydrocarbons forming the recycled mixture. It may further be stated that, according to the present invention, as long as the desired conversion of the nonhalogenated methane is maintained at the product side with the desired product predominating, the composition of the recycling mixture will remain unchanged. Thus the recycling mixture, which is present preferably in a large amount by comparison with the quantity of the methane introduced, functions as a temperature-controlling or temperature-dissipating agent and as a productcontrolling medium. The term halogenated hydrocarbon as used herein is intended to identify hydrocarbons having at least one atom of chlorine or fluorine. It has, however, been found that satisfactory results are obtained when the recycling mixture consists predominantly of one or more of the following compounds: CCL;, CHICI CH CI CFCI and CHCI F. The following additional halogenated hydrocarbons may, etfectively, also be present in the recycling mixture although, in general, they will constitute less than a major portion of the substances recycled: CH CI, CHF CF CI CF Cl, CHF CI, C Cl C Cl C Cl and perchlorobutadiene. T0 obtain the best results, however, it is necessary that the CCI and/or CFCI be present in amounts greater than that of any other component of the recycling mixture. In many cases the most significant results from the point of view of the economics of the reaction were obtained when CCL; plus CFCI represented more than 60% by weight of the recycling mixture.

The recycling mixture can also include one or more inert compounds as well as byproducts of the reaction; thus the recycling mixture can include, for example, some hydrogen chloride produced as a byproduct of the chlorofluorination reaction. In carrying out the reaction, it has been found particularly advantageous to combine the recycling mixture first with molecular chlorine and then with the hydrogen fluoride, the nonhalogenated methane serving as the starting materia]; however, this order of combination of the various components is not imperative.

It has been noted that at molar ratios of the recycling mixture of chlorinated and chlorofluorinated hydrocarbons and the nonhalogenated methane as low as 0.5 the process according to the present invention may still be carried out although some disadvantages, even if only of secondary importance, may result. So t has been observed that a rapid catalyst aging and a consequent poor conversion of hydrogen fluoride take place. Because of the reduccd quantity of recycling mixture and, consequently, its poor eificiency in dissipating the reaction beat, cooling devices or inert diluents, which are difficult to remove from the desired products, must be used. Perhaps most signi-ficantly there is excessive and not always desirable production of very highly fluorinated compounds and a consequent low yield of the lesser fluorinated hydrocarbons; this shift in the orientation of the reaction can be partially avoided only by keeping the conversion of hydrogen fluoride extremely low. At molar proportions of 0.5 or higher (i.e. up to about 15 -moles of recycling mixtures per mole Di nonhalogenated methane), the product contains at least sutficient quantities of the compounds corresponding to those recycled to enable their continuous diversion and reinsertion in the process stream at the reaction zone. There seems not to be an upper lirnt for the molar ratio between the recycling mixture and the nonhalogenated methane except that arising from economica] considerations; nevertheless at molar ratios above about 15:1 there appears to be a reduction in the catalyst utility per unit of nonhalogenated hydrocarbon converted. Thus it is desirable to maintain the molar ratio between the limits oof substantially 0.5:1 to 15:1. In fact, at higher ratios there is no improvement in the orientation of the reaction With respect to the desira ble end products whle there is a necessity for greater plant capacity to process the higher quantities of gases necessary in addition to other obvious inconvenicnces. In general, therefore, the recycled hydrocarbons should constitute, in terms of molar quantities, a substantial fraction of the total fiuorinatable hydrocarbon (i.e., nonhalogenatcd hydrocarbon-i-recycled mixture) fed to the reaction zone or zones. Satisfactory results are obtainable Within this range at molar ratios between upwards of substantially 1:1 to :1, depending upon the desired product, the molar-ratio range of 3:1 to 8:1 being preferred. As Will be apparent from the above-identified applications, moreover, a molarratio range of 5.7:1 to 6.2:1 and a contact-time range of 1.2 seconds to 2.5 seconds yield excellent results.

According to still another feature of the present invention, the gas-phase transformation of nonhalogenated methane into chlorofluorinated methanes is carried out in two reaction zones maintained at difierent temperatures within the range of 180 C. to 700 C.

It has been found that, according to this aspect of the inventon, the subdivision of the reaction into successive reaction zones maintained at diflerent temperatures (at least two such zones being required) not only alfords a better catalyst utilization but also permits a more complete control of the composition of the products as Will become apparent hereinafter. In fact, it appears that the subdivision of the process into at least two reaction stages, in one of which the reaction is carried out over an active fluorination catalyst used alone or together With a chlorination catalyst at a temperature between substantially 180 C. and 350 C. and preferably, beween 200 C. and, 250 C., permits a certain degree of separation between the reactions resulting principally in fluorination of the chloromethanes and those primarily involving chlorinaton; the latter reaction predominatcs in the other reaction stage in which the temperature is maintained between substantially 350 C. and 500 C. and which can include a chlorination catalyst but is also effective when the catalyst has little or no eflectiveness in promoting the reaction except to provide a large contact-surface area. Moreover, the present invention, according to this aspect thcreof, permits the use of catalysts which are temperature sensitive for at least part of the process. Thus, e.g., a. catalyst which has high temperature stability but a rather low catalytic capacity in promotng fluorination can be employed in the high-temperature reaction zone whle a thermally less stable compound having a high fluorination capability is used in the Iowa-temperature zone.

According to the present invention the reactants are preferably passed through the higher-temperature zone and thereafter through the lower-temperature zone, although a rcverse order of flow can also be used albeit With somewhat less effectiveness. It may be noted that some catalysts, when used in a one-zone process, have a tendency to orient the reaction products along certain lines whle the same catalysts are characterized by some- What diferent product mixtures when used in a two-stage process. Ths distinction accounts for the multiple possibilities for exploitation of the heretofore known fluorination and chlorofluon'nation catalysts by the process of the instant invention.

Whereas even inert materials, preferably in a finely divided state, may be employed in the high-temperature zone, it is advantageous when these catalysts are capable of the selectve adsorption of chlorine to promote the chlorination of the hydrocarbons passed therethrough. Thus, activated carbon, metal halides (especially chlorides) and mixtures of such halides and compositions containing metal halides and activated carbons yield the best results. Activated carbons such as peat charcoal,

animal charcoal and vegetable carbon blacks are all suitable for this purpose; the solid materials can be used in the form of powders, shavings, filings, chips, etc. while the activated carbon can be commercially available comminuted charcoals and the like.

The catalysts found to be most advantageous in the low-temperature reaction zone are those found to be advantageous in the single-zone proces described previously, i.e., the supported and unsupportecl oxides and salts of chromiurn, cobalt, nickel, aluminum, thorium, zirconiurn, gallium, vanadium, zinc, iron, copper, bismuth, lead and palladum and especially their fluorides or oxyfluorides. The oxides fiuorides and oxyfluorides can be advantageously dispersed in and npon supports of alumina, fluorinated alumina, actviatcd carbon or barium sulphate.

The lower-ternperature reaction zone can be progressively increased in temperature as the catalyst is consumed or rendered inoperative; thus, an initial reaction temperature of C. can be employed, this temperatuire being progressively increased as necessary up to the levels indicated in connection With the process utilizing a single reaction zone.

The product mixture leaving the reaction zone or zones thus contains, in addition to the desired product or products and the reaction-controlling medium (i.e., the hydrocarbon mixture recycled to the reaction zone), alkalifixable components such as hydrogen chloride (produced during the reactions) and, occasionally, residual hydrogen fluoride and chlorine. Small quantities of excessively fluorinated compounds may also be present. The expression alkali fixable is used herein to denote those substances which can react with alkali (e.g., NaOH, KOH, Na CO in aqueous medium to produce soluble products or precipitates and thereby are removed from the product stream. Water-soluble compounds include those substances which are soluble in water with or without an alkali fixation and can be removed from the product stream by washing With water. The product stream can also contain residual methane or other substances which have a relatively low boiling point, by comparison With the chloro and fluorochloro hydrocarbons predominantly produced in the reaction zone, and are thus less readily condensable npon cooling. Usually the separation of the reaction products, which form the mixture of the recycled halogenated hydrocarbons, is carried out by distillation.

Because of the high value of the condensation heat of the vapors of the fluorinated and chloro-fluorinated organic compounds contained in the reaction mix ture, We have found it desirable to carry out the distillation under pressure.

This pressure dstillation becomes the more profitable the higher the pressure is kept, since the high-pressure conditions permit the use of very inexpensive cooling means for cooling the top of the stripping column, e.g., water. In order to carry out the distillation under high pressure, it is necessary to compress the gas mixture originating from the reaction by means of a compressor. The compressor would have to be built of a special material resistant to the highly corrosive gases present in the gaseous flow coming from the reaction apparatus, e.g., HC1, HF, C1 etc. The use of such equipment having special qualities of cherncal resistance may constitute a drawback, which can be easily overcome by carrying out the gas-phase transforrnation of methane into fluorinated methane at a pressure higher than atmospheric pressure and preferably lying between 2 and 15 kg/cm? The reaction gases thus obtained are conveyed, still under pressure, to a distillation column, at the top of which such gases are partiaily condensed by cooling.

When operating according to this feature of the invention, the gases coming from the reactor, and which are introduced into the distillation column, are already under such pressure conditions that a simple cooling down, for instance by cold water or by brine, depending on the pressure of the gases, is sufficient for obtaining the partial condensation of the reaction products.

By following these procedures, the compression phase of the reaction gases at the outlet of the reactor, usually required when operating at atmospheric pressure, is eliminated since such gases are already at the pressure condition suitable for being partially condensed in the distillation colurnn.

Thus, the necessity of resorting to the use of compressors made of materials of very high chemical resistance is eliminated.

As indicated above, the gases whch react, that is, hydrofluoric acid, chlorine, methane and the recycling mixture, may be easily and without trouble fed to the reactor under pressure. In fact, chiorine and hydrofluoric acid may be supplied in liquid phase by conventional pumps. Methane is compressed to the required pressure by means of a suitable conventional compressor, owing to the non-corrosive nature of the methane itself, while the recycling mixture comng from the bottom of the distillation colurnn, which is already at the pre-established operating pressure, may be supplied by means of a common pump.

It has been found that carrying out the process of the invention accordng to this particular feature ofers many advantages.

The distllation of the reaction process Will take place at such a pressure that it Will be suificient to use very inexpensive means for cooling the top of the stripping column.

The separation of the useful products from the mixture of recycling products is facilitated and simplified while avoiding the need for compressors buiit of specially highly resistant material. Furthermore a vary high productivity of fluorinated and chiorofluorinated methanes per volume unit of catalyst is reached. When operating according to this specific feature of the invention it is also possible to obtain higher conversion of the reactants with higher yields in the desired products even with exceptionally short contact times.

It has also been found that it is particularly convenient to combine the above stated procedure, according to which it is possible to carry out the chlorofluorination of methane in two separated catalysis zones, operating at diierent temperatures, With the procedure relating to the superatmospheric pressure and thus obtain all the advantages which are peculiar to each of these procedures.

EXAMPLE I Into a fluid-bed reactor, whch contained 218 cc. of cutalyst (consisting of fluorinated alumina impregnated 8 With 10% by Weight of ThF and to whch a mixture of halogenated hydrocarbons was recycled continuousiy, a mixutre of hydrogen fluoride, chlorine and methane was fed. At the reactor outiet the products were separated in a continuous manner from the mixture to be recycled and chromatographically analyzed.

The reaction was carried out at 470 C. With a contact time of 1.99 seconds. The composition of the mixture of halogenated hydrocarbons which was recycled continuously was approximately the following:

Mole percent con 80.4 CHCL, 6.0 CH2CL2 0.8 CFC13 12.7

The moiar ratios of the reactants and of the mixture of haiogenated hydrocarbons to be recycled were as follows:

Recycled mixture: C2ZHF1CH4=S.9Z4TL7I1 The conversions of the reactants were the following:

Percent CH 97.4 C1 85.3 HF 98.9

The obtained products and the yields computed on the converted CH were as given below.

Percent CF CI 9.5 CF Cl 73.5 CFCI -15.9

The particle size of the catalyst was about to 325 mesh and the reactor was an Inconel reactor tube contained in an electrically heated furnace. The reactor was equipped with two thermocouples suitably inserted into the cataiyst at distances one third and tWo thirds across the catalytic zone. At the inlet side of the reactor the mixture of methane, chlorine, hydrogen fluoride, and the recycling mixture of halegenated hydrocarbons of the compositions given above and also shown in the accompanying tabie were supplied.

At the outlet side of the reactor, prior to analysis, the gaseous products of the reaction were fed into a stripper where the separation by condensation of the mixture of halogenated hydrocarbons was eifected. Said mixture, in the steady state, was in the same amount and had the same composition as the recycling mixture and was recycled to the inlet side of the reactor as previously described. The residual gaseous products were passed successively through a Water scrubber and a NaOH-solution scrubber to remove HF, chiorine and HC1; they were then passed through a dryer containing CaCI and finally metered and analyzed. The weight-percent composition of the recycling mixture, from which the mole percents above were calculated, are also given in the table.

EXAMPLE II In this experiment, 255 cc. of a catalyst similar to that referred to in the preceding EXAMPLE was used.

The molar composition of the recycling mixture, approximately calculated from the weight-percent values, was:

Mole percent -cc1 81.9 CHCL, 8.9 CHZCIZ 0.9 CH3CI 2.0 CFCI3 6.1

The moiar ratios of the reactants and the halogenated hydrocarbons in the organic recycling mixture were as followsz Reeycled mixture: CI HF:CH =6.I24.611.721

Petcent CH 94.1 C1 82.0 HF 99.5

The products obtained and the yields computed on the converted CH are given in the table:

Percent OF CI 1.8 OF Cl 8412 CFCI 13.6

EXAM P-LE III The reaction was carried out With 287 cc. of a catalyst similar to that used in Example 1.

The composition (calculated from the weight-perment data of the table) of the recycled mixture was the fo1lowing:

Mole percent CCI 76.3 CHCI 14.2 CH Cl 1.2 OH C1 2.3 CFCI 6.0

The mo1ar ratios of the reactants and the halogenated hydrocarbons in the organic recycled mixture were the following:

Recycled mix-ture: C1 :HF: CH.;=5.9:4.7: 1.4: 1

The contact time was 2.4 seconds and the reaction temperature was 400 C.

The conversions of the r-eactants were the following:

Percent CH.; 93.4 C1 78.'6 HF 99.8

The obtained products and the yields computed on converted OH were as follows:

Percent CF CI 0.9

CF C1 48.1

CFCI 50.2

EXAMPLE IV The catalyst was constituted of 320 cc. of carbon With a par-fiele size comprised between 60 and 100 mesh and impregnated With 30% by weight of ThF.;. The recycling mixture had approximately the following molar composition (calculated from the values of the table):

Mole percent CC1 58.9 CFC1 40.8 CHCI 0.1 C C1 0.2 CF CI 0.1

The recycling mixture and the reactants were fed in the following ratios:

Recycled mixture: C1 :HF:CH =6.2:4: 1.3: 1

The contact time was 1.9 seconds and the reaction temperature was 460 C.

The conversions of the reactants We1'e as follows:

Percenrt CH 96.7 C1 95.7 HF 92.6

The products obtained and the net yields computed on the converted methane, as tabulated, were the following:

Percenm CF CI 0.1 CF CI 15.6 CFCI 84.1

EXAMPLE V The reacton is carried out With 322 cc. of fluorinated alumina, of a particle size of 60 to 100 mesh, impregnated With 20% of cobalt fluoride. The approximate composition (calculated from the tabulated data) of the recycled mixture was as follows:

Mole percent cc1 84.5 CFCI3 7.7 CHCI;, 6.3 CHZCI2 0.7 c c1 0.6 c c1 0.1

The molar ratios of the reactants and the recycled organic mixture were as follows:

Recycled mixture: CI :HF:CH =S .7:4.1 1.7: 1

The contact time was 2 seconds and the reaction temperature was 470 C.

The conversion of the reactants was as follows:

Percent CH 99 C1 96 HF 98 The products obtained and the yields as calculated based on the converted methane were as follows:

Percenrt CF CI 8 CF CI 48 CFCI 43 EXAMPLE VI In this experiment 320 cc. of a catalyst constituted of peat coal with a particle size comprised between 35 and 65 mesh, impregnated With a mixture of fluoride and chloride of chromum, was used. The analytic compositon of the catalyst was the following by weight:

C=%, Cr=4.4%, C1=1.4%, F=4.2%

The recycling mixture had approximately the following composition (generally calculated from the weightpercent values of |the table):

The molar ratios of the reactants and of the organic recycled mixture were as follows:

Recycled mixture: CI :HF:CH =S.8:4.I:1.53:1

The contact time was 2 seconds and the reacton temperature was 470 C.

The conversions of the reactants were the following:

Percent CH 99.2 C1 96.5

11 The products obtancd and the yields as computed on methane conversion were as follows:

Percen CF CI 0.6 CF C1 47.7 CFCI;, 51.6

EXAMPLE VII CC14 78.42 c11c1 0.24 CH2C12 0.10 c c1 0.74 C Cl 0.05 CFCI3 20.12 CF2C12 0.12

The recycled mixture and the reactants were fed with the following molar ratios:

Recycled mixture: CI :HF:CH =S.7S:3.Q6: 1.53: 1 The conversions of the reactants were the following:

Percent CH 97.6 C1 98.8 HF 95.6

Products obtained and the net yields as computed on the basis of methane conversion were as follows:

Percent CF;,CI 0.2 CF CI 51.2 CFCI 48.5

EXAMPLE VIII The experiment was carried out using as catalyst 322 cc. of fluorinated alumina impregnated with 5.5% of CI'F3.

The particle size of the catalyst was comprised between 100 and 115 mesh. The composition (approximate as calculated from the tabulatcd data) of the recycled mixture was the following:

Mole percent CCL; 88.07 CHCI 5.76 CH CI 0.68 CFCI 4.13 C C1 1.21 C Cl 0.12

The recycled mixture and the reactants were fed with the following mo1ar ratios:

Recycled mixture: C1 :HF:CH =6:4.3:1.5:1

The contact time was 2 seconds and the reaction temperature was 470 C. The conversions of the. reactants were as follows:

Percent CH 99 C1 92 HF 98 The products and the net yields, based on methane conversions, were as follows:

Percent CF CI 1.5 CF C1 47.8

CFCI3 48.9

1 2 EXAMPLE IX The catalyst was constituted of 560 cc. of fluorinated alumina with particle sizes comprised betwcen and mesh, and the process was carried out at the temperature (470 C.), with the catalyst-contact time (3.0 seconds) and molar ratios of components, and with Ihe recycled composition shown in the accompanying table; the products, yields and conversions are also shown there.

EXAMPLE X The catalyst used was constituted by carbon impregnated with aluminum fluoride, activated and fluorinated at 750 C. The reaction was carricd out under the tabulated conditions yielding the results given in the table.

EXAMPLES XI AND XII The catalyst used was constituted by carbon impregnated with aluminum fluoride and the tabulated process parameters were employed.

EXAMPLE XIII The conditions indcated in the table give the listed results with 450 cc. of vegetal carbon having a granulometry between 35 and 100 mesh (Tyler series) as catalyst.

EXAMPLE XIV 322 cc. of active carbon impregnated with 35% of AIF activated in nitrogen atmosphere and fluorinated with hydrogen fluoride were used as catalyst.

EXAMPLE XV 160 gr. of active carbon were impregnated with 176 cc. of an aqueous solution containing 11.3 g. of ThCl -H 0 and 217 g. of CrC1 -6H O. The mass was dried at C. and hen activated in nitrogen atmosphere at 500 C. and fluorinated at 450 C.

322 cc. of this catalyst were used for this example.

EXAMPLE XVI 322 cc. of active carbon 66 to 100 mesh mpregnated with 10% A1F and activated and fluorinated at 470 C. were used.

EXAMPLE XVII 680 g. of BaSO.; were impegnated with a solution of 1,360 g. of Al(NO '9H O in 2,500 cc. of water.

The mass was dried at 110 C. and heated until disappearance of red gases at 350 C., ground at a granulometry between 42 and 325 mesh, and fluorinated with hydrogen fluoride at 500 C. 350 cc. of this catalyst were used.

EXAMPLE XVIII 1,450 cc. of carbon impregnated with 10% of AIF and fluorinated with hydrogen fluoride at 500 C. were used. In this case the yields calculated with respect to converted methane are:

Percent CO 0.2 CHE, 0.02 CCIF 0.4 CF CI 93.3 CH CI 1.6 CHFCI 0.9 CFC1 3.4

A very small amount of oxygen in the methane accounted for the formation of CO during the reaction.

EXAMPLE XIX Charcoal in vthe form of small cylinders impregnated with 10% by weight of A1F was activated under nitrogen at 450 C. and under hydrogen fluoride at 500 C.

520 cc. of this catalyst were introduced into a conventional type of reactor for catalytic rcactons in fixed bed.

1 3 EXAMPLE XX A mixture of 20% fluorinated alumina and 80% active carbon was used as catalyst.

The yields calculated with reference to converted methane were:

Percent CF CI 2.1 CFCI 90.6 CHFCI 4.2 OH CI 2.1

The entry high boiling in the table identifies a mixture products having a boiling point above 80 C. and comprising some ten to fifteen compounds, mainly C C1 C C1 C C1 C C1 C C1 H EXAMPLE )Q(I The catalyst used was constituted by vegetal carbon having a granulometry between 48 and 100 mesh, impregnated with 10% of FeC1 fluorinated at 200-250 C. with hydrogen fluoride in vapor phase, and then treated for 1 hour at 550 C. with hydrogen fluoride.

The reactor was operated according to the fluid-bed technique.

EXAMPLE XXII The catalyst consisted of carbon Lurgi KT4 having a granulometry between 48 and 100 mesh and was impregnated with ammonium metavanadate (14.3% by weight with respect to the carbon) and with 8.65% by weight of oxalic acid (with respect to the carbon); then the catalyst was treated for 2 hours with N at 300 C. and fluorinated with hydrogen fluoride in the vapor phase at a temperature between 300 C. and 550 C.

The reactor was operated in accordance with the fluidbed technique.

EXAMPLE XXIII In this experiment, the catalyst was constituted by carbon Lurg, KT4 having a granulometry comprised between 100 and 160 mesh impregnated with 10% of CrCl and of CuCl and fluorinated with hydrogen fluoride at a temperature comprised between 150 C. and 250 C. The reactor was operated with the fluid-bed tecbnque.

EXAMPLE XXIV 320 cc. of peat coa1 having a granulometry between 35 and 65 mesh, impregnated with a mixture of fluoride and chloride of chromium, was used as the catalyst.

The analytic composition of the catalyst was the following, by weight: C=90%; Cr=4.4%; Cl=l.4%; F:4.2%.

EXAMPLE XXV The reaction was carried out in two reaction zones.

The first zone consisted of a conventional fixed-bedtype Inconel reactor containing 200 cc. of Inconel filings. The second zone consisted of a similar reactor containing 100 cc. of aluminum fluoride. The temperatures and the contact times of the zones, the molar ratios of the raw materials, the molar quantities and weight composition of the recycling mixture (fed to the first zone) and the product yields and conversions are shown in the Table.

EXAMPLE XXVI Into the first-zone metal reactor (Inconel) containing 240 cc. of a fluid-bed-activated carbon catalyst having a granulometry comprised between 35 and 36 mesh, supported on a porous metal plate, a gaseous mixture of chlorine, hydrogen fluoride and methane and a gaseous mixture of halogenated recycling hydrocarbons were introduced. The starting materials were present in the following molar ratios:

Chlorine 3.9 Hydrogen fiuoride 1.6 Methane 1 Recycling mixture 6 The recycling mxture had the following composition by weight (see the table):

Percent CC1 52.43 CFCI 53.11 CHI-C1 0.22 CH C1 0.17 CHCI 0.85 C C1 2.48 C Cl 0.70

The temperature of the re-actor was ma'intained at 470 C.

The contact time of the gases in the first zone was of 1.5 seconds.

The gaseous mixture from the first zone was then introduced into a second but similar metal reactor containing 118 cc. of a granular fluorinated-alumina catalyst (between about and mesh). The temperature of this second reactor was maintained at about 230 C. The contact time of the gases in this zone was 1 second. On leaving the second reactor the gaseous mixture was conveyed to a stripping column, there the separation of the recycling mixture from the main products and byproducts took place. The recycling mixture was then directly recycled into the first reaction zone. The products were washed with an aqueous solut'ion of sodium hydroxide, condensed and analyzed by gas-chromotography.

The conversions thereby obtained were as follows:

Percent CH 99.3 HF 98.8 C1 97.5

The yields of the desired chlorofluorinated products, calcul-ated on the basis of converted methane, were as follows:

Percent CF CI 1.8 CF CI 60.8 CFCI 37.1

The process was continuously carried out for about 1,000 hours, during which time the catalysts did not show any appreciable reduction of activity.

EXAMPLE XXVII Utilizing the equipment of the preceding ex-ample, a gaseous mixture of chlorine, hydrogen fluoride, methane and a recycling mixture was fed first into the 1ower temperature zone. The starting materials were present in the folloWing molar ratios:

Chlorine 3.82 Hydrogen fluoride 1.71 Methane 1 Recycling mixture 6 The recycling mixture had the foll-owing composition by weight:

Percent CCL; 56.23 CFCI 40.25 CHF C1 0.19 CH CI 0.09 CHC1 0.82 C C1 2.24 C C1 0.52

The catalyst used in the first zone was fluorinated alumina and this first zone was maintained at a tempera- 15 ture of 230 C. The gaseous ingredients from the first zone were then fed into the second reaction zone containing activated-carbon catalyst and maintained at a temperature f 470 C., the contact times were similar to those of Example 26.

In this run the conversions were 'as follows:

Percent CH 100 HP 99.2 C1 97 The net yields of the desired chlorofluorinated products, calculated on converted methane, were as follows:

Percent CF C1 3.6 CF2CI2 75 1 CFCI 21 3 EXAMPLE XXVIII Equipment simlar to that of Exarnples XXV-XXVII was used; the apparatus conssted of a first reactor containing 240 cc. of active carbon (granulometry of 35-60 mesh) maintained at 470 C., and of a second reactor containing 118 cc. of fluorinated alumina impregnated with thorium fiuoride (granulometry 100-11'5 mesh) maintained at 240 C. In the first reactor was introduced a mixture containing chlorine, hydrogen fluoride, methane After 3,500 hours of continuous operation the catalyst did not show any decrease of activity whatsoever.

EXAMP-LE XXIX The first zone of the same apparatus as in the preceding example contained as catalyst fluorinated alumina covered With 1% carbon. The second zone contained alumina activated at 450 C. and fluorinated below 250 C.

EXAMPIJES XXX-XXXIV In order to determine the influence of the molar ratio of recycling mixture to starting hydrocarbons at the reaztion zone, a mixture of hydrogen fluoride, chlorine, methane and a mixture of halogenated hydrocarbons was fed into a single-zone fluid-bed reactor, which contained a catalyst constituted of carbon impregnated with 10% of AlF The halogenated hydrocarbon mixture composition, by Weight, was:

Percent CCL; CFC1 50 The molar ratio of the halogenated hydrocarbons mixture (recycling mixture) to the nonhalogenated aliphatic hydrocarbons is given in the following table from which the conversion and the yield of the process will also be apparent. The reaction temperature was 470 C. and the contact time 3 seconds.

and a recycling mxture having the following molar ratios:

Chlorine 3.9 Hydrogen fluoride 1.44 Methane 1 Recycling mixture 6 The recycling mixture had the following composition in percentage by Weight:

Percent CCL; 40.26 CF C1 0.13 CFC1 5.3.52 CHFCI 0.02 CH CI 0.06 CHCI;; 0.74 C C1 4.12 C C1 1.06

The contact time of such gases in the first reactor was 1.5 seconds, ater Which the gases were transferred to the second reactor, where they remained for one second. The recycling mixture of the above-quoted composition was then removed from the finished reaction products by partial condensation. The resulting product was as follows:

Net yield based upon The accompanying drawing demonstrates the characteristics of the process of the present invention in terms of their dependence upon the molar ratio of recycled halogenated-hydrocarbon mixture to input nonhalogenated hydrocarbon. In the drawing:

FIG. 1 is a graph of the conversion of hydrogen fluorde to the fluorinated hydrocarbon plotted along the ordinate in percent against the molar ratio of recycled balogenated hydrocarbon to nonhalogenated hydrocarbon plotted along the abscissa;

FIG. 2 is a graph of the net yeld of difiuorodichloromethane, one of the most desirable products of the process of the present invention, plotted in percent as the ordinate against the molar ratio plotted along the abscissa; and

FIG. 3 is a graph of the hourly rate of producton, in moles, of fluorinated chloromethanes per liter of catalyst (a measure of reactiom eficiency) plotted along the ordinate against the molar ratio plotted along the abscissa.

T0 determine the influence of molar ratio, as described above, a mixture of hydr0gen fluoride, chlorine, methane and equa1 parts of carbontetrachloride and trichlorofluoromethane (as recycled halogenated hydrocarbon component) was reacted as previously described in a fluidizedbed reactor at a temperature of 470 C., with a catalyst contact time of three seconds and a carbon-supported fluorinated-alumina catalyst. The molar ratios of chlorine and hydrogen fluoride to methane were maintained close to 4:1 and 2:1, respectively, while the molar ratio of recycled hydrocarbons to methane was varied as indicated by the abscissa in FIGS. 1 and 2. These graphs demonstrate that up to a molar ratio of substantially 1:1 a sharp increase in both the hydrogen-fluoride conversion and the yield of the most -desirable product occurs, molar ratios of somewhat less than 1:1 being effective With, however, materially teduced conversions and yields.

EXAMPIJE XXXV Some granulated alumina was ground and sieved; the fraction comprised between 48 and 325 mesh (Tyler series) was treated for 3 hours with air at 500 C. at an air speed of 8 cm. per second. The catalyst was then cooled down to 150 0. and treated with a current of nitrogen and hydrogen fluoride until a complete fluorination was achieved; during ths operation the temperature of the catalyst may not exceed 250 C. Thereupon, 218 cc. of the product obtained was loaded into a fluid-bed reactor.

Reaction conditions and results are tabulated.

As can be seen, under these conditions the CF CI, which in the standard production of chlorofluoromethane is considered as a by-product, was obtained in considerable quantities.

EXAMPIJE XXXVI 120 cc. of the catalyst prepar6d according to the preceding tests were loaded into the second stage of a fluidized-bed reactor in the first stage of which were contained 240 cc. 01: coal marketed under the trademark Lurgi KT4 and having a granulometria size comprised between 35 and 60 mesh (Tyler series).

EXAMPIJE XXXVII In an apparatus substantially identical with that of the preceding example, 120 cc. of the usual catalyst were loaded into the second stage while into the first stage were put 240 cc. of the same catalyst but activated by a long period of operation at high temperatures.

In this case, too, the production of CF Cl was reduced to more than one-tenth of that of Example X)O(V.

From -Examples XXXV-)OCXVII it Will be understood that the same catalyst composition can yield diflerent product mixtures Wth orientation toward the production of greater quantites of one product and lesser quantities of another merely as a consequence of its use in either a single-zone reaction or in a multiple-zone system. Whereas in Example XXXV the fluorinated alumina was employed in a single-stage reaction and yielded considerable quantities of trifluorochloromethane, a less desirable product hawing a higher degree of fluorination, the same catalyst used in the second stage, in accordance with Exarnple XXXVI, resulted in a ten-fold decrease in the yield of the trifluorinated product and a corresponding ncrease in the yield of the monofluorinated product. A similar result was obtained, using the same catalyst, in the twostage process of Example XXXVII.

EXAMPLE XXXVIII The equipment used for the chloro-fluornaton reaction substantially consisted of two metal reactors disposed in series and of a distillation column, both apparatuses suitable for operating under pressure.

Into the first metal reactor containing 372 cc. di activated carbon of a size from 48 to 65 mesh, supported by a porous metal plate,and kept at a temperature of 470 C., was introduced at a pressure of 4 kg./cm. a gaseous mixture consisting of chlorine, hydrofluoric acid, methane and a recycling mixture of halohydrocarbons, according to the following molar ratios:

Moles Chlorine 4.09 Hydrofluoric acid 1.58 Methane 1 Recycling mxture of halo-hydrocarbons 5.8

The reeyclng mxture of halo-hydrocarbons had the following molar composition:

The contact time of the gases in the catalyst zone was of 1.76 seconds.

The gaseous mixture coming out of the reactor was then c'onveyed to the second metal reactor which contained 220 cc. of fluorinated alumina of au to mesh size and was maintained at 235 C.

The contact time of the gases in the second catalysis zone was 1.44 seconds. At the outlet of the second reactor, the gaseous mixture was introduced into a distil- 1'ation column whose top was cooled by brine at about -10 C. At the bottom of the column, a liquid mixture of products was collected which was then drawn out by a metering pump, evaporated and recycled as a recycling mixture, while from the head of the column a gaseous mixture was withdrawn. This gaseous mxture represented the raw reaction material which was subjected to washing and subsequent fractional condensation.

The molar composition of the mixture of the reaction products emerging from the top of the column was:

Moles percent HCI 83 ,23 HF 0.22 C1 1.29 CF CI 0.14 CF2CIz 8.18 CFCI 6.40 CHCL;, 0.01 CH 0.12

The conversiohs of the various reagents and the yields in chloro-fluon'nated products calculated with respect to the converted methane were:

The procuctivity of the catalyst was of 7.22 moles of chloro-fluorocarbons per liter of catalyst per hour.

EXAMPLE XXXIX Using the same equipment as that described in Example XXXVIII, a comparative test at atmospheric pressure was carried out. The compositon of the recycling mixture and the molar ratios o.f the reagents were the same as those recorded in Example )OQCVII. Pressure was 764 mm./Hg.

The temperature of the first reactor was 470 C. and the contact time was 1.49 seconds. The temperature of the second reactor was 230 C. and the contact time was 1 second.

The top of the columns was cooled by trichloroethylene and Dry Ice at about --35 C.

Conversion and yields were obtained which were practically equal to those recorded in Example XXXVIII.

The productvity of the catalyst was 2.02 moles of chlorofluorooarbons per liter of catalyst per hour.

UNITED STATES PATENT OFFICE CERTIFICATE ()F CORRECTION Patent No. v 962 Dat i 1 1969 Invent (s) Martino Vecchio, Italo Cammarata and Luciano Lodi It is certified thai: error appears in the above-identifed patent and that said Letters Patent are hereby corrected as shown below:

In the heading ---Claims priority, application Italy, September 11, 1961, 16, 368/61, Patent 665, 278--- 4 Signed and sealed this 25th day 01 May -1 9?1 (SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attestng Officer Commissioner ci Patents 

